Re: Blockbusting news, results get worse

Pavel Machek
2003-10-28T01:22:13Z

Hi!

> >>or put it under heavy write workload and remove
> >>power.
> >>
> >Can you tell us more about what really happens to disk drives when the
> >power is cut while a block is being written? We engage in a lot of
> >uninformed speculation, and it would be nice if someone who really knows
> >told us....
> >
> >Do drives have enough capacitance under normal conditions to finish
> >writing the block? Does ECC on the drive detect that the block was bad
> >and so we don't need to detect it in the FS?
>
>
> Does it really matter to speculate about this?
>
> If you don't FLUSH CACHE, you have no guarantees your data is on the
> platter.

Well, even without FLUSH CACHE, you can expect that sector being
writen during powerfail either contains old data *or* new data.

If sector can become unreadable after powerfail, I guess journaling
people would like to know, and if powerfail may mean adjacent (or even
unrelated?) sectors to be damaged, everyone needs to know...
Pavel
--
When do you have a heart between your knees?
[Johanka's followup: and *two* hearts?]